Goggles, or protective eyewear or sunglasses having tinted lenses, are advisable and commonly used in connection with certain sports and other hazardous activities to protect the participant's eyes. Eye protection is especially called for when the sport or other activity involves unshielded high-speed travel, since traveling through the air increases the velocity of impact on exposed surfaces of foreign matter that may be encountered. A few examples of sporting activities where eye protection is recommended include downhill skiing, snowmobiling, and motorcycle racing, to keep snow, dust, insects, rocks, etc., out of the wearer's eyes.
The problem of fogging or misting, i.e. the buildup of condensation, on the inside surfaces of eyeglasses is well known. The problem is particularly acute when the wearer is warm and/or perspiring, and the environment is cool and/or damp. The fogging of the lenses obviously interferes with the wearer's vision, and as such is a dangerous condition.
The prior art has long recognized the fogging problem and proposed several solutions. For example, the prior art has proposed thermal lenses, which consist of a single lens of increased thickness operative to isolate the cooler air on the outside from the warmer air on the inside of the glasses. The prior art has also proposed double glass, which consists of dual lenses separated by a layer of air, also operative to achieve the effect of isolating the two sides of the glasses. The thermal lenses and double glass, however, add to the bulkiness and weight of the goggles, and thus they are not desirable.
The prior art has also tried various coatings on the inside surface of the glasses, either to immediately condense or to absorb any misting on the lenses. The water must go somewhere though, making the coatings only effective for a limited duration, after which time the inside of the glasses need to be emptied out or dried off in some manner.
The most promising of solutions proposed by the prior art include attempts to improve the air circulation behind the goggles or eyeglasses, i.e., exhausting the warm humid air and replacing it with cool drier air. The prior art has proposed miniature fans powered by portable batteries carried by the user, a needlessly complex and costly way to resist fogging. Of greater interest, the prior art has also proposed ventilation ports around the perimeter of the glasses' frames, surrounding the lens. Unless properly designed however, the ventilation ports may provide too little air flow, resulting in ineffectiveness or even worse in a suction effect. At the other extreme, the ventilation ports may provide for too great of an air flow, resulting in a pressure build up or in uncomfortably high "winds" across the wearer's eyes. In addition, these ventilation ports may allow in the foreign matter, e.g., dust, that the goggles or eyeglasses are envisioned to guard against.
In view of the shortcomings of the prior art, it is desirable to provide effective eyeglasses, that safely protect a wearer's eyes and are not subject to fogging. The eyeglasses should be low cost by being simple to manufacture. Finally, the eyeglasses must be lightweight so as not to interfere with the wearer's sporting activities.